Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure     

Sandermann H 《Pest management science》2004,60(7):613-623

Plants are well known to incorporate pesticides into bound and unextractable residues that resist solubilization in common laboratory solvents and are therefore not accessible to standard residue analysis. A characterization of such residues has been proposed for incorporation rates above trigger values of 0.05 mg kg(-1) parent pesticide equivalents, or percentage values of 10% (United States Environmental Protection Agency, 1995) or 25% (Commission of the European Communities, 1997) of the total radioactive residue. These trigger values are often exceeded. The present review describes the current status of the chemical characterization and animal bioavailability of bound and unextractable residues that may be xenobiotic in nature or result from natural recycling of simple degradation products. The latter case represents a mechanism of detoxification. Bound residues have been shown to be covalent or non-covalent in nature. With regard to the plant matrix molecules involved, incorporation into proteins, lignins, pectins, hemicelluloses and cutins has been demonstrated, and four covalent linkage types are known. Animal feeding experiments have revealed cases of low as well as high bioavailability. Many of the studies are limited by experimental uncertainties and by results only being reported as relative percentage values rather than absolute exposure. A preliminary value of absolute exposure from bound and unextractable residues is derived here for the first time from eight case studies. The mean exposure (ca 1.5 mg kg(-1) pesticidal equivalents) exceeds some of the existing maximum residue levels (MRLs) of residual free pesticides that are typically in the range of 0.05-1 mg kg(-1). A mathematical framework for the correction of current maximum residue levels is presented for cases of highly bioavailable bound residues. As bound pesticidal residues in food plants could represent a source of significant consumer exposure, an experimental test scheme is proposed here. It consists of basic chemical characterization, model digestibility tests and, in exceptional cases, animal bioavailability and additional toxicological studies.  相似文献   

Spin coupling in engineered atomic structures     

Hirjibehedin CF  Lutz CP  Heinrich AJ 《Science (New York, N.Y.)》2006,312(5776):1021-1024

We used a scanning tunneling microscope to probe the interactions between spins in individual atomic-scale magnetic structures. Linear chains of 1 to 10 manganese atoms were assembled one atom at a time on a thin insulating layer, and the spin excitation spectra of these structures were measured with inelastic electron tunneling spectroscopy. We observed excitations of the coupled atomic spins that can change both the total spin and its orientation. Comparison with a model spin-interaction Hamiltonian yielded the collective spin configuration and the strength of the coupling between the atomic spins.  相似文献   

Cataract in the UK Leonberger population     

Heinrich CL  Lakhani KH  Featherstone HJ  Barnett KC 《Veterinary ophthalmology》2006,9(5):350-356

OBJECTIVE: To survey the Leonberger, a numerically small breed in the UK, for the presence of cataract and find statistical support for the possible presence of inherited forms of cataract. METHODS: Ocular examinations were carried out by the first author between September 1996 and September 1998 on 211 Leonbergers; results of the ocular examination of further 228 Leonbergers examined between January 1990 and September 1998 by members of the British Veterinary Association/KC/ISDS eye scheme (BVA/KC/ISDS eye scheme) panel were analyzed. Data from all dogs examined were pooled in a composite database of 365 Leonbergers and the relationships between offspring and parents for the identified forms of cataract were examined with appropriate statistical methods. RESULTS: Cataracts were diagnosed in 90 Leonbergers, the majority being nuclear (40) or posterior polar subcapsular (31). A subgroup of nuclear cataracts, diagnosed in 11 dogs, is described and named as 'posterior nuclear cataract.' For posterior polar cataract, a positive association between offspring and parents was made in the logistic regression model, supporting the suggestion of inheritance. CONCLUSIONS: The presence of several types of cataract in the UK Leonberger population is described. Statistical support for the inheritance of posterior polar subcapsular cataract is given.  相似文献   

Solar wind neon from Genesis: implications for the lunar noble gas record     

Grimberg A  Baur H  Bochsler P  Bühler F  Burnett DS  Hays CC  Heber VS  Jurewicz AJ  Wieler R 《Science (New York, N.Y.)》2006,314(5802):1133-1135

Lunar soils have been thought to contain two solar noble gas components with distinct isotopic composition. One has been identified as implanted solar wind, the other as higher-energy solar particles. The latter was puzzling because its relative amounts were much too large compared with present-day fluxes, suggesting periodic, very high solar activity in the past. Here we show that the depth-dependent isotopic composition of neon in a metallic glass exposed on NASA's Genesis mission agrees with the expected depth profile for solar wind neon with uniform isotopic composition. Our results strongly indicate that no extra high-energy component is required and that the solar neon isotope composition of lunar samples can be explained as implantation-fractionated solar wind.  相似文献   

Why Do Localities Provide Economic Development Incentives? Geographic Competition,Political Constituencies,and Government Capacity     

Michael R. Betz  Mark D. Partridge  David S. Kraybill  Linda Lobao 《Growth and change》2012,43(3):361-391

U.S. states and localities often engage in economic development policies using incentives and abatements for specific firms or industries. Yet, there is very little empirical evidence suggesting that such policies are successful. Why, then, do governments engage in these policies? In order to answer this question, we employ a model that considers not only geographic and economic factors, but also, in a novel application, local political conditions. A unique survey of U.S. county governments forms the basis for our empirical assessment of both traditional economic development policies and new‐wave policies. Using probit, Poisson, negative binomial, and spatial econometric models, we find evidence that the use of incentives is inversely related to local economic conditions. Furthermore, we find Republican counties are more apt to use incentives, though counties dominated by one political party are less likely to use them.  相似文献   

Bactericidal properties of pradofloxacin against veterinary pathogens     

Silley P  Stephan B  Greife HA  Pridmore A 《Veterinary microbiology》2012,157(1-2):106-111

Pradofloxacin is a new veterinary 8-cyano-fluoroquinolone developed for use against bacterial infections in dogs and cats involving both aerobic and anaerobic bacteria. The minimal bactericidal concentrations have been determined against clinical isolates of Staphylococcus pseudintermedius, Staphylococcus aureus, Escherichia coli, Pasteurella multocida, Streptococcus canis, Proteus spp., Fusobacterium spp., Porphyromonas gingivalis and Prevotella species. A subset of these species was selected, and the in vitro rate of kill by pradofloxacin was determined. For 27 of the 30 tested aerobic strains the pradofloxacin MBC was within two doubling dilutions of the MIC. For the remaining strains, the MIC and MBC were within three to four doubling dilutions. Pradofloxacin also demonstrated bactericidal activity against all anaerobic strains, and the MBC was equal to the MIC for four of the strains, within 1 doubling dilution for three strains, within 2 dilutions for a further 3 strains and within 3 dilutions for the remaining five strains. As pradofloxacin concentration was increased, a faster rate of killing was observed; bactericidal effects were seen in all cases at concentrations ≤ 0.25 μg/mL. The bactericidal activity against the anaerobic strains was marked, of particular relevance was the complete absence of regrowth even at 48 h at concentrations as low as 0.125 μg/mL. In conclusion, pradofloxacin exhibits clear bactericidal activity in terms of MBC and kill kinetics against aerobic and anaerobic clinical isolates from dogs and cats at concentrations that are greatly exceeded within the systemic circulation after administration of the recommended therapeutic doses to the target animals. It is expected that such a rapid rate of kill will play a significant role in clinical efficacy. These data demonstrate the complete and rapid killing of anaerobic bacteria by a veterinary 8-cyano-fluoroquinolone.  相似文献   

Age effects and climate response in trees: a multi-proxy tree-ring test in old-growth life stages     

Isabel Dorado Li?án  Emilia Gutiérrez  Ingo Heinrich  Laia Andreu-Hayles  Elena Muntán  Filipe Campelo  Gerhard Helle 《European Journal of Forest Research》2012,131(4):933-944

Aging in trees implies a progressive reduction in the growth rate, related to a shortening of the growing period and changes in the photosynthetic capability and efficiency. These changes may continue during the old-growth life stages following the juvenile phase and are reflected in tree-ring properties such as growth increment, density or stable isotopes. We studied possible climate age effects in time series of several tree-ring parameters (ring width, wood density and stable carbon and oxygen isotopes) of mature individuals from two age groups of Pinus uncinata and P. nigra at two locations in Spain. The aim was to test whether age differences in trees in the old-growth life stages could lead to diverging climate responses. The results show some differences in response to climate between age groups at a monthly level, but most of these divergences are not significant for seasonal climate variables. Regardless of the age group, the main limiting climate factors constrained tree growth equally. Although our findings do not support the idea of an age-dependent response to climate that may lead to inaccurate climate reconstructions, further studies using tree-ring density and stable isotope series are urgently needed to verify the current results.  相似文献   

On the Current Situation of Glanders in Various Districts of the Pakistani Punjab     

Iahtasham Khan  Lothar H. Wieler  Mahboob Ahmad Butt  Mandy C. Elschner  Ashiq Hussain Cheema  Lisa D. Sprague  Heinrich Neubauer 《Journal of Equine Veterinary Science》2012

Glanders is a highly infectious and zoonotic disease of solipeds caused by Burkholderia mallei. Progressive loss of efficiency and fatal outcome resulted in massive economic losses, which forced veterinary authorities throughout the world to implement disease control measures; these measures included mass testing using the complement fixation test and/or malleinization, and the culling of positives. This led to the eradication of glanders from Western Europe and North America in the 1950s. However, in the last decade, the number of outbreaks in Asia and South America increased steadily, and glanders regained the status of a re-emerging transboundary disease. Pakistan has been an endemic country for the past 120 years, but concise data on the presence of disease are not available. A total of 533 serum samples were collected from draught equines, a suspected risk group for glanders, from various districts of Punjab in Pakistan. The complement fixation test and the highly sensitive Western blot technique were used for serodiagnosis. No animal (horse, mule, and donkey) was found to be positive for infection. Glanders seems to be restricted to remote, sporadic pockets of endemicity and may cause outbreaks after being introduced into naive populations by (asymptomatic) shedders.  相似文献   

Effect of oxytocin infusion on luteal blood flow and progesterone secretion in dairy cattle     

Christos N. Brozos  Metin S. Pancarci  Javier Valencia  Nikola Beindorff  Georgios Tsousis  Evaggelos Kiossis  Heinrich Bollwein 《Journal of veterinary science (Suw?n-si, Korea)》2012,13(1):67-71

The objective of this study was to investigate the effects of oxytocin infusion on corpus luteum (CL) function during early to mid-diestrus by measuring luteal size (LS) and luteal blood flow (LBF) along with plasma levels of progesterone (P4) and prostaglandin metabolites (13,14-dihydro-15-keto-prostaglandin F_2α, PGFM). On day (D) 7 of the estrus cycle (D1 = ovulation), seven cows received 100 IU of oxytocin (OXY) or placebo (PL) following a Latin square design. LS and LBF increased in both groups over time and no differences were observed between the groups. PGFM did not differ either within the groups over time or between the groups at any time point. P4 of the OXY group was higher compared to that of the the PL group 360 min after the infusion (p = 0.01) and tended to be higher at the time points 450 min, 48 h, and 72 h (all p = 0.08). Results from this study support the hypothesis that OXY is not directly involved in the mechanism(s) governing blood flow of the CL and has no remarkable effects either on luteal size or P4 and PGFM plasma levels. Further investigation is needed to elucidate the role of OXY in CL blood flow during early and late luteal phases.  相似文献   

Parotid duct transposition in dogs: a retrospective review of 92 eyes from 1999 to 2009     

Rhodes M  Heinrich C  Featherstone H  Braus B  Manning S  Cripps PJ  Renwick P 《Veterinary ophthalmology》2012,15(4):213-222

Objective The aim of this study was to perform a retrospective review of parotid duct transposition (PDT) in the dog to determine the rate and nature of complications, the success and failure rates and to evaluate owner satisfaction. Methods Medical records of 56 dogs (92 eyes) that underwent PDT and subsequent follow‐up by a veterinary ophthalmologist were reviewed. Forty owners (40 dogs/66 eyes) were contacted by telephone and 37 owners (37 dogs/60 eyes) also completed a visual analog scale questionnaire. Statistical evaluation included Wilcoxon Signed Rank tests, one‐way analysis of variance and Kaplan–Meier survival analysis with Wilcoxon and Log‐rank tests. Results The mean follow‐up was 38.7 months (range 1–109 months). The surgical success rate was 92% (85/92 eyes). Total failures (8%, 7/92 eyes) were because of severe saliva intolerance (n = 5 eyes) and PDT failure (n = 2 eyes). The complication rate was 50% (46/92 eyes) of which 61% (28/46 eyes) were managed medically and 39% (18/46 eyes) required further surgery. Ninety percent (36/40) of owners indicated that they would proceed with surgery again. Statistically significant improvements in owner perception of ocular comfort, number of daily topical treatments, ocular wetness, and postoperative vision were identified. Conclusions This study shows that PDT is a successful procedure based on clinical findings and in terms of owner perception. It has also demonstrated that PDT improves ocular comfort and vision in medically refractive cases of keratoconjunctivitis sicca, and that a low level of on‐going management is required in 33% of cases.  相似文献